Gluing machine



current through a resistance.

Patented Mar. 31, 1953 UNITED STATES TET OFFICE GLUING MACHINE GillespieApplication July 26, 1946, Serial N 0. 686,520

2 Claims.

-The present invention relates to gluing machines in general andparticularly to a gluing machine adapted to secure together a pluralityof narrow strips of wood to form a relatively wide panel or board and ina time period only a. fraction of that ordinarily required for such anoperation. More specifically, the invention comprises a panel gluingmachine in which the gluing together of relatively narrow strips of woodis accelerated by means of electrostatic heating to form relativelylarge panels and in a period of time which is but a fraction of the timenormally required for the glue to set.

In. the manufacture of furniture and other articles of wood it. has beenfound both desirable and economical to manufacture large area panelsfrom narrow wood strips. By the older method a suitable adhesive or glueis placed upon adjacent surfaces which are then clamped together and,set away to dry over an extended period of time. The time required forthe glue to set was a matter of hours and depended upon the temperatureof the ambient atmosphere. This operation required. large drying roomsand the continuous use of clamps until the glue had set. In certaininstallations conveyor racks were provided upon which the clamped panelswere suspended and by which they were carried to and from the dryingroom. To speed the operation heating means were also provided in someinstallations to raise the drying temperatures, a

step which served to increase still further thecostof the operation.

The apparatus constructed in accordance with the present inventioneliminates the use of clamps, heating rooms and conveyors and effects asufi'lcient adhesion of the glue by theapplication of electrostaticheating for a period of a fraction of a minute to cause the strips toadhere without further assistance.

The drying of the glue to effect the substantial instantaneous adhesionof the wooden strips is, according to the present invention, effectedelectrostatically. There are a plurality of electric heating methods.The simplest comprises conduction in which the heat is derived fromenergy dissipated by the passage of electrical To use such heat ing'means adjacent a wooden element, however, would produce scorching of thewood if the temperature were raised to a point sufficiently high to drythe glue instantaneously or substan tially instantaneously. Where thearticle to be heated is metallic, use may be made of induction heatingin which a magnetic field is set up by an induction coil near thearticle to be heated producing, if the field is oscillatory, eddycurrents in the article which are dissipated as heat energy. This methodof heating is not available in the use of wood which is a non-conductor.

Still another type of heating is known as electro-magnetic heating inwhich energy in the form of electro-magnetic radiation is absorbed in abody and converted thereby into heat. Infra-red heating is a specialform of this type of heating since the incandescent filament of the bulbradiates electro-magnetic energy in the infra-red wave lengths, whichare absorbed by the body to be heated. This type of energy is absorbedby both conductors and dielectrics.

A further type of heating, and this is the'type which is used in thepresent invention, comprises electrostatic or dielectric loss heatingand is operative by virtue of the fact that most materials when used asdielectrics are imperfect and so have dielectric losses. When amaterial, such as Wood for example, is placed between the plates of acapacitor as a dielectric, it will be heated as the electricaldielectric loss is converted into heat. In such heating, frequencies ashigh as 50 megacycles are common.

In the apparatus comprising the present invention, use is made of theelectrostatic method of heating and means are provided by which the woodstrips to be glued are advanced on a conveyor into the presence of theheating means, at which point they are compressed and forced together bypressure exerted from all sides. The creation of intense heat thereinfor a limited period of time by positioning plates connected to a sourceof high frequency current upon the opposite sides thereof, effects asubstantially instantaneous drying of the glue, or at least of certainportions thereof and produces what can be termed spot gluing. Uponrelease of the pressures and the removal of the panel, the multiplicityof spots which are glued provide a sufficient holding force to securethe entire panel together and it may be transported without particularcare and stacked and permitted to dry completely without further specialattention.

It is an object of the present invention to provide a new and improvedgluing machine for wooden panels in which a multiplicity of relativelynarrow wooden strips are glued together by the application ofelectrostatic heat over an extremely short time interval to effectsuificient adhesion as to permit the panel to be removed and treated asa unit without special care.

It is a further object of the invention to provide a gluing machineconstructed and arranged as to feed successive groups of relativelynarrow wooden strips into the presence of clamping and electrostaticheating means to produce substantially instantaneous gluing of thestrips to an extent sufficient to eliminate the necessity for subsequentretaining clamps and heated drying rooms.

These and other more specific objects will appear upon reading thefollowing specification and claims upon considering in connectiontherewith the attached drawings to which they relate:

Referring now to the drawings in which a preferred embodiment of theinvention is disclosed,

Figure 1 is a side elevation of a machine constructed in accordance withthe present invention; and

Figure 2 is a horizontal section through the machine looking in thedirection of the arrows upon the line 2-2 of Figure 3; and

Figure 3 is a front view of the machine; and

Figure 4 is a diagrammatic showing of the intersections of the plates orcontacts and the planes of the joints of the wooden strips and shows thepoints at which maximum adhesion is effected; and

Figure 5 is an enlarged partial section through the contacts of theelectrostatic heating means and shows a panel in place therebetween; and

Figure 6 is a View in perspective showing the panel supporting conveyor,with its movable contact plates; and

Figure 7 is a diagrammatic showing of the valve-controlledpressure-acted clamping means.

The panel gluing machine constructed in accordance with the presentinvention comprises five main or principal parts which may be called thesupporting base or frame, indicated generally in the drawings by thereference character H; the conveyor system indicated generally in thedrawings by the reference character [2; the pneumatic clamping means,indicated generally by the reference character E3; the high frequencydrying means, including the high frequency current generating unit andthe contacts, indicated generally by the reference characters 14 and I5;and the semi-automatic control means.

The relationship of and the cooperation between these various parts willnow be described.

The frame The frame of the unit is shown most clearly in Figures 1, 2and 3 and is seen to comprise an elongated table formed with supportinglegs Ii between which extend longitudinal top elements I 8 andtransverse top elements !9. The forward end of the table is made widerthan the rearward part to provide supporting means for the horizontalclamping means later to be described. To insure rigidity and relativelygreat strength, horizontal and vertical brace members 2! and 22 areprovided between the legs and below the top members it and, in thepreferred form, all of the elements are fabricated of metal. The base orframe is relatively strong being intended and adapted at its forward endto support working parts weighing several hundred pounds. The entireunit is preferably secured fixedly in place upon a supporting floor toreduce vibration and possible dislocation.

The conveyor system The conveyor system is shown clearly in Figures 1,2, 3, 5 and 6 and comprises a rear, or

feeder unit, and a forward or gluing unit. These units form in fact oneconveyor being aligned and interconnected to travel at the same rate ofspeed. Referring first to the feeder unit, it is seen to be mounted uponthe top of table II and to comprise a pair of parallel spaced endlesschains extended longitudinally of the machine adjacent the frame topmembers 18 and carried by sprockets 24. The latter are fixed upon shafts26 rotatably mounted in bearings 2'! secured on members !8.

A multiplicity of cross pieces or support elements 28 are secured tochains 23 at spaced intervals to form the supporting surface of theconveyor unit and, as is clearly shown in Figure 2, provide a flat bedupon which a plurality of parallel wooden strips 29 are adapted to lie.Side rails 3| extend adjacent the ends of the elements 28 to preventaccidental lateral displacement of pieces 29, being connected to andsupported on the frame top elements l8 by a plurality of upright members32.

The feeder conveyor unit, as the name indicates, is a feeding unit, butit also serves as the initial assembly point at which the strips 29 tobe glued together into a panel are assembled with their adjacent edgescoated with an adhesive. At the proper time the unit functions, as willbe described, to advance the strips on the forward conveyor unit wherethe heat treatment takes place.

The forward conveyor unit also comprises longitudinally extending spacedchains, here indicated by the reference character 36. Each chain, andthere are three, is again carried at its forward and rearward ends by asprocket 31 fixedly mounted upon a rotatable shaft 38. The latter issupported at its ends in bearings 39 mounted on the top of frame sidemembers l8. As in the case of the rear or feeder conveyor, transversecross pieces or elements, indicated at 4|, are spaced at equal intervalsalong the chains to form a bed or support surface. In the present case,however, for reasons which will be apparent, the upper or supportingedge of each element 4| is provided with a metallic electricalconductor, strip, or plate [4 connected at one end to an electricalwiper or brush 42.

To drive the conveyors there is provided an electric motor 46 positionedbelow the top of the frame ll on the level of braces 2!, 22 and suppliedwith current by a conduit 41 connected to a switch 48 which may be ofthe solenoid-controlled type. The incoming current to the switch 48enters by the conductor indicated by the reference character 49. Powerfrom the driving motor 46 is transmitted through an endless belt 5| to aspeed reducing unit 53 which includes a slow speed rotary shaft 54carrying a sprocket 56. A power transmitting chain 51 extends upwardlyfrom sprocket 56 to a second sprocket 58 positioned upon the conveyorshaft 38 at the front of the machine. Energization and rotation of themotor is effective to rotate that shaft at reduced speed and, as allthree chains 35 are all connected to sprockets 31 carried by front shaft38, it is clear that its rotation will effect the travel of the frontconveyor.

To transmit the actuating force from the front to the rear or feederconveyor a power transmiting chain 59 is connected, as shown in Figures1 and 2, between sprockets SI and 62 positioned respectively upon theshaft 38 at the rearward end of the front conveyor and upon the shaft 26at the forward end of the feeder conveyor. Actuation of the frontconveyor is automatically effecconveyor and at the same rate of speed,sprockets GI and 62 being of the same diameter. As the forward and rearconveyor units are spaced slightly a supporting roller 66 is providedtherebetween. The latter is supported at its ends in bearings upon frameside elements I8 and is positively driven by a chain (i9 which extendsfrom a sprocket it on the roller shaft to a driving sprocket 12 on theadjacent shaft 38 of the front conveyor. Upon energization of the motor,because of the interconnections present, the front conveyor unit, therear conveyor unit, and the roller (it are simultaneously actuated.

As will be explained subsequently a downward clamping pressure isexerted upon the wooden strips 29 when positioned upon the forwardconveyor unit and to withstand this pressure, reinforcing means areprovided for the front conveyor chains 35. These means take the form ofelongated rigid metallic channels It in which the upper half of eachfront conveyor chain slides. Channel members 'I=6 are themselvessupported by spaced transverse wooden beams or supports 11 the ends ofwhich rest upon the longitudinal frame elements I8.

It is the purpose of the forward and rear conveyors which have beendescribed to feed the panel elements into position for heating, to sup--port it during the heat treatment and in the presence of considerablepressures forcing the elements together, and then to discharge thetreated panel from the machine. The means by which the clampingpressures are exerted during the heat treatment will now be described.

The clamping means With the narrow wooden strips 29 positioned upon theforward conveyor in. position to be heat treated, the clamping meansperform their function of. bringing the elements tightly together toforce the adhesive positioned upon adjacent surfaces into the.interstices of. the wood and to expel the excess. Turning first to thehorizontal or lateral compression. means, they are seen to comprise abank of. pneumatic rams 8| mounted upon the widened forward portion oftable II at the side of the front conveyor and in substantialhorizontal. alignment with. the. top surface thereof. Each ram comprisesas shown in Figure "I, a

fixed cylinder 82 slidingly seating a piston 89 and from which extends apiston rod 83. The latter carries at its forward end an abutment element84 adapted to make contact with the outside wooden strip 29 and to forceit against the strip adjacent thereto. At the opposite side of theconveyor is a rigid abutment or side wal1 86 positioned upon the crossbeams IT and having a height sufficient to obstruct the lateraldisplacement of the elements 29 under the horizontal force exerted bythe rams '8 I.

The rams 8| are identical and are pneumatcasing H2 asdoes one or moreexhaust outlets ically operated. Air conduits B8 and 89 connect to theopposite ends: of each cylinder '82, their own opposite ends connectingto a source of pneumatic pressure comprising a conduit Iii, through amanually controlled valve 93. The latter includes a casing 94 and amovable valve element 96. In Figure '7, valve 93 is showndiagrammatically with movable element '98 positioned so that air underpressure passes from conduit Ii-I, through the casing 9i and conduit 83,and into the cylinder 82 to exert a pressure upon one side of the piston80. Movement of the piston under this pressure will effect the exhaustof air from cylinder 82 upon the opposite side of piston '80. Theexhausted air passes through the conduit t9 into valve casing 94 andtherefrom through the exhaustpipe 91. Manual reversal of the position ofvalve element 96 connects conduit 89 to the pressure source, effectsmovement of the piston in the opposite direction, and exhausts air fromthe cylinder 82 through conduit '88. The manual operation of the valve93 is seen to control the direction of movement of the ram piston '80and enables the operator to cause the abutment 84 to move into abuttingand pressure exerting contact with the panel elements 29, or to bewithdrawn therefrom.

In addition to the exertion of a transverse compressing force by therams 8i, it is desirable also that a vertical force be exerted tomaintain the elements in alignment and against any possible buckling andalso to move the upper contacts I4 downwardly into contact with thepanel. To effect these results, a plurality of identical vertical ramsII are provided, each comprising a casing I I12 housing a slidabl'episton I03 from which extends a piston rod I04 carrying at its lower endan abutment head I06. As in the case of rams BI, conduits, hereindicated by the reference characters I93 and IE9, extend from oppositeends of the cylinder I02 to a manuallycontrolled valve indicatedgenerally at III and which includes a casing I I2 and a manually movablevalve element H3. A conduit H4, leading to a source of air pressure,connects to the valve H t. With the valve element H3 positioned as shownin Figure '7, the piston IE3 is forced downwardly by the pressure of airfrom the conduit I 89, the air within the lower portion of the cylinderand below the piston: being forced therefrom through conduit I [18,valve chamber I I2 and outlet II'B. Upon reversal of the position ofvalve element I I3 as to connect pressure conduit IN to conduit Iii'B,the direction of piston movement is reversed.

The abutment head' tilt. at the lower end of the piston rods I84 of eachram Hi2 comprises three laterally extending. spaced abutment elements orpieces I-ZI connected by a header I22 directly secured to the lower endof rod 594. The upper contact elements It are secured to the lower facesof the pieces I2 I. A coil spring I23 encircles each piston rod ltdabove the. abutment head I06 and acts as a shock absorber and to limitthe upward movement of the head under piston actuation.

The various rams BI act in. synchronism as do the various rams I-III,making it possible for the functionally similar conduits leading theretoto be joined into a single conduit leading to the,

valve chambers as shown in Figures 1 and 3. Also, it is possible for asingle incoming source of air pressure in a conduit 26 to be connectedto both oi the pressure conduits 'SI and I It leading to valves 93 and III, respectively. Because of this interconnection and relationship,-theoperation of a single set. of valves 93 and IEI effects the joint and.synchronous. operation of all rams BI and all rams 'IIlI respectively,the rams BI preferably being actuated first.

The high frequency heating means It has. previously been described thatcontacts.

or plates- M are carried by the cross pieces ll of the front conveyorunit and by the side elements I2.I of the abutment head I06, as shownmost clearly in Figure 5. The strips of wood 29 which are to be gluedtogether to form a single unitary panel are positioned during theheating operation upon the cross pieces 4! and are subjected to thevertical and horizontal compression by the rams 8| and IIlI as describedunder the preceding title. Were the strips to be held for a suflicientlength of time, the glue between the strips would set without more beingdone but clearly this would result in the tying up of the completemachine for a matter of hours. This time interval is reduced to a matterof seconds by the provision of high frequency current in the contacts I4in contact with opposite sides of the strips. The contacts, which extendperpendicularly across the strips in the manner illustrateddiagrammatically in Figure 4, have impressed upon them a high frequencycurrent to heat the glue electrostatically. The current impressed may bein the range-of 50 megacycles and is conducted to the upper contacts I4by means of a flexible buss bar I21 which is itself connected through aconductor I28 to the high frequency current-generating unit I5. Thelower contacts I4, being movable, are connected at their ends, aspreviously described, to wiping brushes 42 which make contact with astationary buss bar I3I carried by the abutment or side wall 86. Thecurrent is conducted to the latter from the generating unit I through aconductor I32.

High frequency current generating unit I5 may be of a commercial typeand does not constitute the essence of the present invention. It isadapted to be supplied with line voltage current from an external sourceat ordinary 50 or 60 cycles and to convert that current into current ofextremely high frequency through the use of vacuum tube circuits for thepurpose described. The unit is preferably contained within a singlecasing and may well be positioned adjacent the gluing machine proper, asillustrated in Figures 2 and 3. Suitable controls may be provided bywhich the unit is energized when initially placed into operation anddeenergized at the end of the working period.

Control of the feeding operation To simplify the duty of the operator,means are provided which render it necessary only to push a button inorder. to displace the panel which has just been formed and to advanceinto operative position the strips to be treated. These means comprise amaster control switch, indicated generally at I33, including a manuallyoperable starting button I34 and an automatic stop or cut-out buttonI36. Switch I33 is connected by means of conductors positioned within aconduit I 37 with switch 48 which may, as previ ously indicated, be ofthe solenoid type.

To actuate master switch I33 automatically, a rotatable gear MI ismounted upon the side of frame II adjacent its forward end and conveyorshaft 38 thereabove is connected therewith by means of a pinion I42which it carries. Gear I4I comprises a rotatable cam by virtue of thepresence of a sloping cam element I43 positioned on its side near itsperiphery. Element I43 is so located and proportioned as to ride underand lift the end of a lever I44 which is pivoted centrally at I46 on theframe II so that its opposite end extends into operative abuttingcontact with the stop or cut-out switch button I36. The purpose of thecam is to eifect the pivotal movement of the lever as to actuate stopbutton I36 and thereupon deenergize the driving motor 46 upon gear I4Ihaving made one complete revolution. The relationship is such that gearI4I makes one complete revolution upon the advance of the conveyorsystem suificiently to move the strips 29 from the feeder conveyor ontothe forward conveyor and into operative position.

Operation In the operation of the present invention the wooden strips 29are first covered with glue upon their edges and are laid parallel uponthe feeder conveyor at the rear of the machine as shown in Figures 1 and2. The button I34 is then pushed by the operator, resulting in theenergization of the motor 46, which drives the conveyors to move thepanel forwardly into operative position below the abutment heads I06.Upon reaching this position the cam gear I4I has rotated through 360 andthe cam element I43 causes the lever I44 to pivot to actuate the pushbutton I36 whereupon the motor is deenergized and the conveyor movementstopped.

As will be noted from an examination of Figure 5, the conveyor movementis stopped in such relative position of the upper and lower bars orcontacts I4 that each contact in one group (upper or lower) liessubstantially midway between two adjacent bars of the other group. Thus,it will be seen that when the upper contacts are pressed downwardlyagainst the strips 29, the spans of the latter supported on two adjacentconveyor bars M are bent downwardly somewhat, the amount of bendingbeing dependent upon the degree of pressure exerted by the uppercontacts and the longitudinal spacing of the contacts. As can be seen inthe drawings, the spacing betwen adjacent spacer bars is several timesthe thickness of the planks so that an appreciable bend of the strips 29is possible without excessive clamping pressure.

Accordingly, if one of the strips 29, as often happens, is slightlythicker than the others, such thicker strip is bent downwardly,permitting each contact I4 to make a uniform and continuous contactacross the panel, thus contacting each of the several glue joints.

The high frequency generating unit I5 has previously been energized bythe usual means and is ready to perform its heating function upon thebringing into operative juxtaposition of the contacts I4. Before this isdone, however, the operator manually turns valve element 96 to theposition shown in Figure 7, thereby causing pistons in each of the rams81 to advance with the abutment elements 84. The latter force the woodenstrips 29 together as the strip upon the outer edge is forced, againstthe side wall or abutment 86. The operator, then positions manuallyoperable valve element I I3 in the position shown in Figure 7, therebycausing air to pass through pipe I09 into the top of cylinder I02 toforce the piston I03 downwardly. This operation takes placesimultaneously in each of the pneumatic rams I02 and the plungers I04force the abutment heads I06 into contact with the underlying woodenstrips, that is, into the position shown in Figure 5.

The relationship then existing between the contacts or plates I4 is suchthat the retention of the heads in the lowered position for a fractionof a minute effects the heating and drying of the glue by means ofelectrostatic heating. The frequency of the current is such as to effectprimarily the drying of the glue and such drying is believed to takeplace With maximum effectiveness at the lines of intersection of thecontacts and of the glued surfaces as indicated in Figure 4. Upon theelapse of the predetermined time period, a matter of seconds and lessthan one minute, the operator changes the position of valve element H3to permit air to be directed from the inlet pipe H4 through pipe I08 tolift the piston I03 in each of the rams Illl. Heads I06 are thereuponcarried upwardly, the coil springs I23 serving as bumpers to prevent thepiston striking the upper end of the cylinder.

With the abutments I06 raised, the operator then reverses the positionof valve element 96 to cause air to be forced through conduit 89 intothe forward end of cylinder 82. Thereupon the pistons 80 move theabutment elements 84 from the panel which is now, so far as anyreasonable separating force is concerned, a unitary structure. Thereuponthe operator again energizes motor 46 by pushing button I34 to cause arepetition of the feeding operation previously described which this timeincludes the advance of the treated panel out of the machine, a suitablereceiver or attendant disposing of the panel.

While the particular apparatus herein shown and described in detail isfully capable of attaining the objects and providing the advantageshereinbefore stated, it is to be understood that it is merelyillustrative of the presently preferred embodiment of the invention andthat no limitation is intended to the details of construction or designherein shown other than as defined in the appended claims.

We claim:

1. In apparatus for edge gluing a plurality of longitudinally disposedplanks positioned in side by side relationship, into a unitary panel,clamping and glue setting means comprising in combination: a first groupof transverse bars uniformly spaced apart by several times their widthand disposed in a common plane; a second group of transverse bars spacedapart as said first bars,

and disposed in a common plane opposed to, and

substantially parallel to said first bars; means to support said secondgroup of bars for longitudinal movement in said second plane to carryplanks supported thereon into and out of the space between said bars;means to halt the movement of said second bars in a position thereofwherein a bar in said second group lies longitudinally intermediate twoadjacent bars in said first group; and pressure means connected to saidfirst group of bars to urge the same toward said second plane toslightly bend planks lying in said space between said planes.

2. In apparatus for edge gluing a plurality of longitudinally disposedplanks positioned in side by side relationship, into a unitary panel,clamping and glue setting means comprising in combination: a firstgroupof transverse bars uniformly spaced apart by several times theirwidth and disposed in a common plane; a second group of transverse barsspaced apart as said first bars, and disposed in a common planesubstantially parallel to said first plane; means to support said secondgroup of bars for lo'ngitudinal movement in said second plane to carryplanks supported thereon into and out of the space between said bars;drive means connected to said support means to move said bars asaforesaid; means synchronously connected to said drive means to halt themovement of said second bars in a position thereon wherein a bar in saidsecond group lies longitudinally intermediate two adjacent bars in saidfirst group; and pressure means connected to said first group of bars tourge the same toward said second plane to slightly bend planks lying insaid space between said planes.

FOREST H. GILLESPIE. CHARLES FRANZEN. DOMINIC P. MOTTA.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 869,923 Mereen et al. Nov. 5,1907 1,296,424 Peace Mar. 4, 1919 1,916,134 Dike June 27, 1933 1,977,199Osgood Oct. 16, 1934 2,071,999 Dike Feb. 23, 1937 2,231,457 Stephen Feb.11, 1941 2,253,713 Lancaster Aug. 26, 1941 2,288,269 Crandall June 30,1942 2,290,762 Miller July 21, 1942 2,291,807 Hart Aug. 4, 19422,317,281 Linquist Apr. 20, 1943 2,347,604 McDonald Apr. 25, 19442,457,498 Russell et al Dec. 28, 1948 FOREIGN PATENTS Number CountryDate 871,825 France Jan. 22, 1942

